Device for measuring optical charateristic of eye

ABSTRACT

The position of an object surface is detected with an error reduced on a reflectance boundary surface. A first light source ( 100 ) emits the luminous flux of the first wavelength. A first illumination optical system ( 200 A) illuminates a small area on a retina ( 61 ) to be examined by the first luminous flux from the first light source ( 100 ). A first reception optical system ( 300 A) guides a part of the luminous flux which is reflected by and retuming from the retina ( 61 ) to be examined to a first light reception part ( 510 ) via a first conversion member ( 400 ) for converting the reflected luminous flux into at least 17 beams. A second light source ( 110 ) emits the luminous flux of the second wavelength. A second illumination optical system ( 200 B) illuminates a predetermined area on the retina ( 61 ) to be examined by the second luminous flux from the second light source ( 110 ). A second reception optical system ( 300 B) guides the second luminous flux reflected by and returning from the retina ( 61 ) to a second light reception part ( 520 ). A display part checks at which position on the fundus oculi ( 61 ) of the eye ( 60 ) the luminous flux for measurement is converged or fixed, and the position of convergence and the position of measurement are changed by using a drive unit to move a fixation mark or the irradiation position of the irradiation light for Hartmann measurement.

TECHNICAL FIELD

The present invention relates to a device for measuring an opticalcharacteristic of an eye, and particularly to a device for measuring anoptical characteristic of an eye, which irradiates a fundus of an eye tobe examined with a luminous flux and measures the optical characteristicof the eye by reflected light therefrom.

BACKGROUND OF THE INVENTION

As a conventional corneal shape measuring device, there is known adevice which projects a mark, obtains an imaging position of the mark,and measures a corneal shape. Besides, as a device for measuring anoptical characteristic of an eye, there is a device for which thepresent applicant filed patent application and in which focus adjustmentof an illumination optical system is performed according to the level ofreceived light of a first light receiving part, and focus adjustment ofa light receiving optical system is performed on the basis of an opticalcharacteristic (S) obtained from the output of the first light receivingpart (Japanese Patent Application No. 9-137630).

SUMMARY OF THE INVENTION

In the conventional device for measuring the optical characteristic ofthe eye to be examined, it was impossible to confirm to which positionon the fundus the measurement luminous flux is irradiated. Thus, therealso occurs a case where the measurement is performed while the fixationis insufficient, and there has occurred a request to confirm to whichposition on the fundus the measurement luminous flux is irradiated.

The present invention has been made in view of the above circumstancesand has an object to provide a device for measuring an opticalcharacteristic of an eye in which it is possible to confirm at whichposition on a fundus of an eye to be examined a luminous flux formeasurement is converged or fixed, and a fixation target or anirradiation position of irradiation light for Wavefront sensing usingShack-Hartmann method is moved so that the position of convergence andthe position of measurement can be changed, and the reliability of datais further raised.

According to the invention, a device for measuring an opticalcharacteristic of an eye includes

a first light source for emitting a luminous flux of a first wavelength,

a first illumination optical system for performing illumination by afirst illumination luminous flux which is from the first light sourceand is converged to a vicinity of a center of a fundus of an eye to beexamined,

a second light source for emitting a luminous flux of a secondwavelength,

a second illumination optical system for illuminating an observationarea of the fundus of the eye to be examined by a second illuminationluminous flux from the second light source,

a beam splitter for branching a reflected luminous flux reflected fromthe fundus of the eye to be examined into a first branch luminous fluxcontaining most of the reflected luminous flux of the first wavelengthand a second branch luminous flux containing a remaining portion of thereflected luminous flux of the first wavelength and the reflectedluminous flux of the second wavelength,

a first reception optical system for receiving the first branch luminousflux branched by the beam splitter and for guiding the first branchluminous flux so as to be received through a first conversion member forconverting it into at least 17 beams,

a first light receiving part for receiving the first branch luminousflux from the first reception optical system,

a second reception optical system for guiding the second branch luminousflux branched by the beam splitter so as to be received,

a second light receiving part for receiving the second branch luminousflux from the second reception optical system,

an arithmetic part for obtaining an optical characteristic of the eye tobe examined on the basis of an inclination angle of the luminous fluxobtained by the first light receiving part, and

a display part for enabling confirmation of an irradiation position ofthe first illumination luminous flux on the fundus by a signal from thesecond light receiving part.

Some features of the embodiment will be exemplified below.

In order to know a converging point of the measurement light on thefundus, an optical system which enables observation of the fundus isprovided. Besides, the fixation or the measurement light is moved sothat the measurement light is converged on a specified position on thefundus and an incident position is changed.

In this embodiment, a wavelength of a fundus observation system and ameasurement wavelength are slightly changed. For example, fundusillumination is made to have 860 nm, and a measurement wavelength of aHartmann plate is made 840 nm. Then, at a light path dividing place of ameasurement system, a beam splitter is put which transmits, for example,light of 860 nm, transmits 5% of light of 840 nm and reflects 95%thereof. These values are merely examples, and can be suitably changed.

A projection of the fundus observation system is made, for example, aring-shaped or circular projection, and reflection by a cornea or a halfway corneal vertex and reflection of a vertex of an optical lens areprevented. Besides, the light source is conjugated with a pupilposition.

Methods of moving projection light on the fundus include two methods,that is, a method of moving the fixation, and a method of movingillumination light for eye optical characteristic measurement.

In the case where the illumination light for eye optical characteristicmeasurement is moved, galvanometer mirrors are put at two places, andthe mirrors are respectively inclined in an x direction and a ydirection, so that the incident position is changed. When a desiredincident position is obtained, swing is made there in a minute angle,and uneven reflection due to disturbance on the retina is removed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing a schematic optical system of an eyecharacteristic measuring device 1000 of a first embodiment of theinvention.

FIG. 2 is a view showing a schematic optical system of an eyecharacteristic measuring device 2000 of a second embodiment of theinvention.

FIG. 3 is a view showing a schematic optical system of an eyecharacteristic measuring device 300 of a third embodiment of theinvention.

FIG. 4 is an electric system block diagram showing an electric structureof the eye characteristic measuring device 1000 of the first embodimentof the invention.

FIG. 5 is a flowchart of the eye characteristic measuring device 1000 ofthe first embodiment of the invention.

FIG. 6 is a flowchart showing a specific measurement method of the eyecharacteristic measuring device 2000 of the second embodiment of theinvention.

FIG. 7 is a view (1) showing a display example of a fundus image.

FIG. 8 is a view (2) showing a display example of a fundus image.

FIG. 9 is a view (3) showing a display example of a fundus image.

FIG. 10 is a view showing an example of a characteristic view of a beamsplitter.

FIG. 11 is an explanatory view showing a display example graphicdisplayed on a display part 700.

FIG. 12 is a flowchart concerning Wavefront sensing using Shack-Hartmannmethod.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

1. Optical System

(First Embodiment)

Hereinafter, an embodiment of the present invention will be described indetail with reference to the drawings.

FIG. 1 is a view showing a schematic optical system of an eyecharacteristic measuring device 1000 of a first embodiment of theinvention.

The eye characteristic measuring device 1000 includes, for example, afirst light source part 100, a first illumination optical system 200A, afirst reception optical system 300A, a first light receiving part 510, asecond light source part 110, a second illumination optical system 200B,a second reception optical system 300B, a second light receiving part520, a third light source part 91, a third reception optical system 30,a first adjusting optical system 50, and a third illumination opticalsystem 90. Incidentally, with respect to an eye 60 to be examined, aretina (fundus) 61 and a cornea (anterior eye part) 62 are shown in thedrawing.

The first light source part 100 emits a luminous flux of a firstwavelength. The first illumination optical system 200A illuminates aminute area on the retina 61 of the eye to be examined by the firstluminous flux from the first light source part 100. The first receptionoptical system 300A guides, for example, a part of the luminous fluxreflected by and returning from the retina 61 of the eye to be examinedto the first light receiving part 510 through a first conversion member400 for converting the reflected luminous flux into at least 17 beams.The second light source part 110 emits a luminous flux of a secondwavelength. The second illumination optical system 200B illuminates aspecified area on the retina 61 of the eye to be examined by the secondluminous flux from the second light source part 110. The secondreception optical system 300B guides the second luminous flux reflectedby and returning from the retina 61 of the eye to be examined to thesecond light receiving part 520.

Hereinafter, the respective parts will be described in detail.

The first illumination optical system 200A is for illuminating, forexample, the minute area on the retina 61 of the eye to be examined bythe luminous flux from the first light source part 100. The firstillumination optical system 200A includes a first converging lens 210, afirst relay lens 220 and a lens stop 230.

It is desirable that the first light source part 100 has high spatialcoherence and not high temporal coherence. Here, as an example, an SLDis adopted as the first light source part 100, and a point light sourcewith high brightness can be obtained. Incidentally, the first lightsource part 100 is not limited to the SLD, and even if both the spatialand temporal coherences are high like a laser, it can be used byinserting a rotation diffused plate or the like to suitably lower thetemporal coherence. Then, even if both the spatial and temporalcoherences are not high like the LED, if only the quantity of light issufficient, it can be used by inserting a pinhole or the like at aposition of a light source in an optical path. Besides, as thewavelength of the first light source part 100 for illumination, forexample, a wavelength in an infrared range, for example, 780 nm can beused. In the case where the first light source part 100 is continuouslyturned on, the luminous flux for optical characteristic measurement andthe luminous flux of the anterior eye part 62 of the eye to be examinedas an object to be examined are simultaneously received by the firstlight receiving part 510.

The first reception optical system 300A is for receiving, for example,the luminous flux reflected by and returning from the retina 62 of theeye to be examined through a second beam splitter 340 and for guiding itto the first light receiving part 510. The first reception opticalsystem 300A includes a first a focal lens 310, a second relay lens 320,the second beam splitter 340, and the conversion member 400 forconverting the reflected luminous flux into at least 17 beams.

The conversion member 400 disposed in the first reception optical system300A is a wavefront conversion member for converting the reflectedluminous flux into plural beams. Incidentally, here, pluralmicro-Fresnel lenses disposed on a plane orthogonal to the optical axisare adopted as the conversion member 400.

The first light receiving part 510 is for receiving the light havingpassed through the conversion member 400 and from the first receptionoptical system 300A and for generating a first signal. With respect tothe first light receiving part 510, the first light source part 100 andthe fundus 61 are conjugated with each other, and the fundus 61 and thefirst light receiving part 510 are conjugated with each other. Further,the lens stop 230, the conversion member 400 and the pupil are alsoconjugated with one another. That is, the front focal point of the firsta focal lens 310 is substantially coincident with the anterior eye part62 of the eye 60 to be examined as the object to be examined. Thereflected light from the fundus 62 passes through the first a focal lens310 and the relay lens 320, and is converged on the first lightreceiving part 510 through the conversion member 400.

Then, the first illumination optical system 200A and the first receptionoptical system 300A are moved in synchronization with each other, whileon the assumption that the luminous flux from the first light sourcepart 100 is reflected at a converged point, such a relation that thesignal peak at the first light receiving part 510 by the reflected lightbecomes maximum is kept, and they are moved in a direction in which thesignal peak at the first light receiving part 510 becomes high, and arestopped at the position where the intensity becomes maximum. As aresult, the luminous flux from the first light source part 100 isconverged on the eye 60 to be examined.

The second illumination optical system 200B is for illuminating aspecified area on the retina of the eye to be examined by the secondluminous flux from the second light source part 110. The second lightsource part 110 is for emitting the luminous flux of the secondwavelength of, for example, 860 nm. The second light source part 110 isa point light source or a surface light source to the fundus 61 and canbe made to have a near-infrared region. When the wavelength of the firstlight source part 100 for Wavefront sensing using Shack-Hartmann methodis 840 nm, and the wavelength of the light source part for the anterioreye part illumination is 940 nm, infrared or near-infrared light otherthan those, for example, a suitable wavelength of 850 to 930 nm (atpresent, for example, 860 to 880 nm) between them can be selected. Thesecond illumination optical system 200B includes, for example, thesecond light source part 110, a fourth converging lens 250, and a mirror290 with a hole. With respect to the illumination of the fundus 61, inthis example, the illumination light for an observation area of thefundus 61 is formed using the mirror 290 with the hole. The center ofthe ring-shaped lens stop transmits 100% of light, the transmittance ofits periphery is made, for example, about 10%, and the peripheryilluminates the whole of the fundus. The second light source part 110 isconjugated with the pupil (imaged on the pupil), and most of the fundusis wholly and uniformly illuminated by this. Besides, the mirror 290with the hole has a conjugated relation with the pupil so as to preventthe reflection at the corneal vertex. In the second reception opticalsystem 300B and the second light receiving part 520, it is possible toobserve the converging point on the fundus by the first light sourcepart 100, and both the observation system by the second light sourcepart 110 and the fixation target by the third light source part 91.

The second reception optical system 300B includes, for example, thefirst a focal lens 310, a first beam splitter 330, the mirror 290 withthe hole, and a second converging lens 350. The light of the secondwavelength reflected by a beam splitter 280 formed between the firstbeam splitter 330 and a beam splitter 285 is guided to the second lightreceiving part 520 through the first beam splitter 330 and the secondconverging lens 350. The second light receiving part 520 generates asecond signal. The beam splitter 285 is constructed by, for example, adichroic mirror which reflects the luminous flux of the first wavelengthand transmits the luminous flux of the second wavelength. The secondlight receiving part 520 for receiving a formed fundus image isconstructed of a light receiving element having sensitivity to infraredlight. Besides, a rotary prism 332 for making the light uniform isdisposed between the second beam splitter 340 and the beam splitter 285.The rotary prism 332 is conjugated with the pupil.

The third reception optical system 30 includes relay lenses 31, 32 and33, a telecentric stop 34, and a third light receiving part (here, forexample, an anterior eye part observation CCD) 35. The third receptionoptical system 30 guides a luminous flux, which is formed such that apattern of a Placido's disk 41 illuminated from a light source partincluded in the first adjusting optical system 50 is reflected by andreturns from the anterior eye part 62 of the eye 60 to be examined, tothe third light receiving part 35. Besides, the telecentric stop 34 is,for example, a lens stop for preventing the anterior eye part image fromblurring. The pupil and the telecentric stop 34 are conjugated with eachother.

The first adjusting optical system 50 is for, for example, mainlyperforming a working distance adjustment, and includes light sourceparts 51 and 55, converging lenses 52 and 53, and a light receiving part54. Here, the working distance adjustment is performed such that, forexample, a parallel luminous flux emitted from the light source part 55and near the optical axis is irradiated to the eye 60 to be examined,and the light reflected by the eye 60 to be examined is received by thelight receiving part 54 through the converging lenses 52 and 53.Besides, in the case where the eye 60 to be examined is in a suitableworking distance, a spot image from the light source part 55 is formedon the optical axis of the light receiving part 54. On the other hand,in the case where the eye 60 to be examined falls outside the suitableworking distance, the spot image from the light source part 55 is formedabove or below the optical axis of the light receiving part 54.Incidentally, since the light receiving part 54 has only to detect achange in luminous flux position on a plane including the light sourcepart 55, the optical axis and the light receiving part 54, for example,a one-dimensional CCD disposed on this plane, a position sensing device(PSD) or the like can be applied.

The third illumination optical system 90 includes an optical path forprojecting a target for fixation of the eye to be examined or fogging,and includes the third light source part (for example, lamp) 91, afixation target 92, and a relay lens 93. The fixation target 92 can beirradiated toward the fundus 61 by the luminous flux from the thirdlight source part 91, and the eye 60 to be examined is made to observeit. The fixation target 92 can be made a landscape chart, a circularopening or the like, and the third light source part 91 can be made toemit visible light or near-infrared light, and when the near-infraredlight is used, its image can be measured by the second light receivingpart 520 of the second reception optical system 300B. The fixationtarget 92 and the fundus 61 are conjugated with each other.

(Second Embodiment)

FIG. 2 is a view showing a schematic optical system of an eyecharacteristic measuring device 2000 of a second embodiment of theinvention. Incidentally, blocks and structures overlapping with those ofthe eye characteristic measuring device 1000 are denoted by the samesymbols, and their functions and structures are the same.

In the eye characteristic measuring device 2000, the guidance of an eye60 to be examined to a specified position can be performed by themovement of a fixation target or the use of a prism. Specifically, inthe movement of the fixation target, a fixation target 92 of a thirdillumination optical system 90 can be moved in a direction orthogonal toan optical axis. Besides, in the use of the prism, the prism is insertedafter a relay lens 93, and the optical axis can be moved.

(Third Embodiment)

FIG. 3 is a view showing a schematic optical system of an eyecharacteristic measuring device 3000 of a third embodiment of theinvention. Incidentally, blocks, structures and the like overlappingwith those of the eye characteristic measuring device 1000 are denotedby the same symbols and their functions and structures are the same.

In the eye characteristic measuring device 3000, two galvanometermirrors 286 and 287 are inserted between a second beam splitter 340 anda beam splitter 285. Here, in the eye characteristic measuring device3000, in the case where projection light of a conversion member 400 ismoved, the galvanometer mirrors 286 and 287 are respectively inclined inan x direction and a y direction to change an incident position. When adesired incident position is obtained, swing is made in a minute angle,and uneven reflection due to disturbance on the retina can be removed.

2. Electric System

(First Embodiment)

FIG. 4 is an electric block diagram showing an electric structure of theeye characteristic measuring device 1000 of the first embodiment of theinvention.

An electric driving system of the eye characteristic measuring device1000 includes an arithmetic part 600, a control part 610, a display part700, a memory 800, a first drive part 910, a second drive part 911, athird drive part 912, and a fourth drive part 913. The arithmetic part600 includes an imaging state changing part for changing a state at thetime when wavefront measurement is performed, and a measurement part forperforming various eye characteristic measurements.

Besides, the arithmetic part 600 is constructed such that a first signal{circle over (4)} from the first light receiving part 510, a secondsignal {circle over (5)} from the second light receiving part 520, asignal {circle over (7)} from the third light receiving part 35, and asignal (14) from the light receiving part 54 are inputted. Thearithmetic part 600 obtains the optical characteristic of the eye 60 tobe examined on the basis of the first signal {circle over (4)} from thefirst light receiving part 510, and detects the illumination state ofthe first illumination optical system 200A on the basis of the secondsignal {circle over (5)} from the second light receiving part 520.Besides, the arithmetic part 600 outputs signals corresponding to thearithmetic results to the control part 610 for controlling the whole ofthe electric driving system, the display part 700 (various displayexamples will be described later) and the memory 800.

The arithmetic part 600 obtains, for example, the optical characteristicof the eye 60 to be examined on the basis of the first signalcorresponding to the inclination angle of the luminous flux and from thefirst light receiving part 510, and detects the illumination state ofthe first illumination optical system 200A on the basis of the secondsignal from the second light receiving part 520.

The imaging state changing part changes the imaging state of the firstillumination optical system 200A and the first reception optical system300A into the first change state in accordance with the level of thefirst signal {circle over (4)} from the first light receiving part 510,and then, changes the imaging state of the first illumination opticalsystem 200A and the first reception optical system 300A into the secondchange state in accordance with the optical characteristic obtained bythe arithmetic part 600. Incidentally, here, although the firstwavelength is set to be shorter than the second wavelength, the relationmay be inverted.

The control part 610 is for controlling the switching on and off of thefirst light source part 100 on the basis of the control signal from thearithmetic part 600 and for controlling the first drive part 910 to thefourth drive part 913. The control part 610, on the basis of the signalsaccording to the arithmetic result at the arithmetic part 600, outputs,for example, a signal {circle over (1)} to the first light source part100, outputs a signal (12) to the second light source part 110, outputsa signal (11) to the third light source part 91, outputs a signal (13)to the light source part 55, outputs a signal {circle over (8)} to thelight source part 51, and outputs signals to the first drive part 910 tothe fourth drive part 913.

The first drive part 910 is for moving, for example, the firstillumination optical system 200A and the first reception optical system300A in the optical axis direction on the basis of the light receivingsignal {circle over (4)} inputted to the arithmetic part 600 from thefirst light receiving part 510, outputs a signal {circle over (3)} to anot-shown suitable lens movement unit, and drives the lens movementunit.

The second drive part 911 is for moving, for example, the secondreception optical system 300B in the optical axis direction on the basisof the light receiving signal {circle over (5)} inputted to thearithmetic part 600 from the second light receiving part 520, outputs asignal {circle over (6)} to a not-shown suitable lens movement unit, anddrives the lens movement unit.

The third drive part 912 is for rotating, for example, the rotary prism332, outputs a signal (10) to a not-shown suitable lens movement unit,and drives the lens movement unit.

The fourth drive part 913 is for, for example, moving the thirdillumination optical system 90, outputs a signal (15) to a not-shownsuitable movement unit, and drives the movement unit. By this, thefourth drive part 913 can move and adjust the fixation target 92 of thethird illumination optical system 90.

(Second and Third Embodiments)

Incidentally, the eye characteristic measuring device 2000 furtherincludes another drive part which outputs a signal {circle over (9)} toa not-shown suitable movement unit, and drives the movement unit so thatthe fixation target 92 of the third illumination optical system 90 canbe suitably moved in the x direction and the y direction. Besides, theeye characteristic measuring device 3000 further includes another drivepart which outputs a signal (16) to a not-shown suitable movement unitand drives the movement unit so that the galvanometer mirrors 286 and287 can be suitably inclined in the x direction and the y direction.

3. Flowchart

(First Embodiment)

FIG. 5 is a flowchart of the eye characteristic measuring device 1000 ofthe first embodiment of the invention. Incidentally, the flowchart hereis for observing the fixation target at the fundus 61 of the eye 60 tobe examined and the irradiation position of light for wavefront sensingusing Shack-Hartmann method.

When measurement is started (S101), the alignment adjustment of theposition of the eye 60 to be examined is performed (S103) . Here, forexample, the control part 610 controls a specified drive part on thebasis of the control signal from the arithmetic part 600, and moves theoptical axis of each of the optical systems to the origin position(S103). Incidentally, with respect to the alignment of the eyecharacteristic measuring device at the cornea, it is appropriate thatillumination is performed by a luminous flux in parallel, a bright pointoccurs at a position of ½ of a corneal radius, and the alignment isperformed by this. By the third light source part 91 and the thirdillumination optical system 90, the exhibition of the fixation target isperformed (S105). By the signal from the second light receiving part 520of the second reception optical system 300B, the arithmetic part 600displays a fundus image on the display part 700 (S107).

Here, the fundus image will be described.

FIG. 7 is a view (1) showing a display example of the fundus image. Thefundus 61 is wholly uniformly displayed by the luminous flux from theillumination light source part (here, the second light source part 110)for illuminating the fundus 61. The fundus image includes, in additionto the fundus 61 of the eye 60 to be examined, a macula 63, and an opticdisk 64, a fixation target luminous flux 921 (in the drawing, ∘) fromthe third illumination optical system 90 including the third lightsource part 91 and the fixation target 92, a Center luminous flux ofwavefront sensing using Shack-Hartmann method 1001 (in the drawing, ▪)showing the center of the incident light of the first light source part100, and a center line 65 of the second light receiving part 520 as afundus observation CCD. Besides, in the case where the alignmentadjustment is performed at the step S103, the fixation target luminousflux 921 and the Center luminous flux of wavefront sensing usingShack-Hartmann method 1001 are positioned at the center of the centerline 65, and are coincident with each other. There is also a case wherethe fixation target luminous flux 921 is not observed.

Next, it is judged whether or not the macula 63 is displayed at thecenter (position of the fixation target luminous flux 921, and theCenter luminous flux of wavefront sensing using Shack-Hartmann method1001) of the center line 65 of the fundus image displayed at the stepS107 (S109). In the case where the macula 63 is out of the center line65, a return is made again to the step S103, and the alignmentadjustment is performed. In the case where the measurement at the macula63 is performed, for example, when a subject is instructed to stare atthe fixation target luminous flux 921, and the macula 63 is normallymoved and comes to include the fixation target luminous flux 921 (in thedrawing (b)). Incidentally, a object may perform this judgment by thedisplay part 700, or the arithmetic part 600 may perform the judgmentprocessing by an image processing technique or a pattern recognitiontechnique. Besides, construction can also be made such that the pictureimage indicating the fundus image at the step S107, especially thepicture image of the fundus image at the measurement is stored and isdisplayed at a later date, together with the measurement result. Bydoing so, it becomes possible to confirm to which position on the fundusthe measurement luminous flux is irradiated when the measurement ismade.

After the step S109, the measurement of the optical characteristic ofthe eye 60 to be examined is performed by the first reception opticalsystem 300A and the first light receiving part 520 (S117), and thearithmetic operation is performed by the arithmetic part 600 (S119) (thedetails will be described later). Next, the arithmetic part 600 displaysthe arithmetic result of the step S119 on the display part 700 (S121:described later). Next, it is judged whether or not the measurement isto be ended (S123), and in the case where it is to be ended, themeasurement is ended (S125). On the other hand, in the case where themeasurement is not ended, a return is made again to the step S103, andthe alignment adjustment is performed.

In the above example, the description has been give to the case wherethe eye to be examined is made to start at the fixation target, and themeasurement is performed in the state where the measurement luminousflux is coincident with the macula. However, according to circumstances,there is also a case where even if the the subject is urged to stare thefixation, the macula and the measurement luminous flux do not overlapwith each other. At that time, the measurement is performed in the stateas it is, and this can be confirmed by the image at the measurement.Besides, as the need arises, the the subject is urged to stare thefixation, and the measurement is made in a natural viewing state, thatis, the judgment of the step S109 can also be omitted. Incidentally, inthe foregoing, although the description has been given on the assumptionthat both the luminous flux of the fixation target and the measurementluminous flux can be observed, in the first embodiment, for the purposeof confirmation, it is sufficient if the luminous flux of the fixationtarget and the measurement luminous flux are coaxial, and one of theluminous flux of the fixation target and the measurement luminous fluxcan be observed.

(Second Embodiment)

FIG. 6 is a flowchart showing a specific measurement method of the eyecharacteristic measuring device 2000 of the second embodiment of theinvention. Incidentally, processings overlapping with those of theflowchart of the eye characteristic measuring device 1000 are denoted bythe same symbols and their functions are the same.

Here, as described above, after the processings of steps S101 to S107are performed, in the case where the macula 63 is substantiallycoincident with the center of the center line 65 at step S109 (FIG.7(a)), the arithmetic part 600 judges whether or not the measurement isat the macula 63 by the memory 800 or inputted instructions (S111).Incidentally, a object may previously input the instructions in thememory 800, or may input them at this time.

Here, at the step S111, in the case where the measurement is not at themacula 63 (for example, in the case where the measurement is desired atan intended position of the fundus image), for example, the fixationtarget luminous flux 921 is moved (step S113). A description will begiven to a case where the fixation target luminous flux 921 is moved atthe step S113.

FIG. 8 is a view (2) showing a display example of the fundus image.

Here, the second adjustment optical system 90 is driven by the drivepart, so that the position of the fixation target 92 is changed, and thefixation target luminous flux 921 is also moved as shown in the drawing.At this time, it is ideal that the macula 63 follows the movement of thefixation target and moves. Thus, for the purpose of confirming theposition of the macula 63, it is judged whether or not a specifiedmeasurement position (state where the fixation target luminous flux 921is contained in the macula 63) is obtained (S115). Incidentally, aobject may perform this judgment by the display part 700, or thearithmetic part 600 may perform the judgment processing by an imageprocessing technique or a pattern recognition technique. Thereafter, thearithmetic part 600 performs the processings of steps S117 to S125 asdescribed above.

In the foregoing, the description has been given to the case where whenthe subject is urged to stare the fixation, the fixation targetcoincides with the macula position. However, according to the eye to beexamined, there is also a case where even if the the subject is urged tostare the fixation, the fixation target does not coincide with themacula position. In such a case, when the measurement is desired in astate where the measurement luminous flux is irradiated to the macula,it is also possible to make the measurement center luminous flux 1001coincident with the macula by moving the fixation target luminous flux921.

(Third Embodiment)

Next, a flowchart of the eye characteristic measuring device 3000 of thethird embodiment will be described. As the flowchart showing itsspecific measurement method, at the step S113 in the second embodiment,instead of moving the fixation target luminous flux 921, the foregoinggalvanometer mirrors 286 and 287 are inclined, and the Center luminousflux of wavefront sensing using Shack-Hartmann method 1001 is moved.

A description will be given to a case where the Center luminous flux ofwavefront sensing using Shack-Hartmann method 1001 is moved at the stepS113.

FIG. 9 is a view (3) showing a display example of the fundus image.

Here, the first illumination optical system 200A is driven by the firstdrive part 910, or the galvanometer mirrors 286 and 287 are driven bythe first drive part or the driving means (16), so that the position ofthe Center luminous flux of wavefront sensing using Shack-Hartmannmethod 1001 is changed, and the Center luminous flux of wavefrontsensing using Shack-Hartmann method 1001 is also moved as shown in thedrawing. At this time, for the purpose of confirming the position of theCenter luminous flux of wavefront sensing using Shack-Hartmann method1001 and the macula 63, it is judged whether or not a specifiedmeasurement position (state in which the fixation target luminous flux921 is contained in the macula 63, and the Center luminous flux ofwavefront sensing using Shack-Hartmann method 1001 does not coincidewith the fixation target luminous flux 921) is obtained (S115).Thereafter, the arithmetic part 600 performs the processings of stepsS117 to S125 as described above.

In the foregoing, the description has been given to the case where whenthe subject is urged to stare the fixation, the fixation targetcoincides with the macula position. However, according to the eye to beexamined, even if the the subject is urged to stare the fixation, thereis also a case where the fixation target does not coincide with themacula position.

In such a case, when the measurement is desired in a state where themeasurement luminous flux is irradiated to the macula, this can be usedin moving the measurement center luminous flux 1001 so that it coincideswith the macula.

4. Beam Splitter

FIG. 10 shows an example of a characteristic view of a beam splitter.

The characteristic of the beam splitter 285 can be made thecharacteristic as shown in the drawing. The characteristic as the bandpass filter is such that most of the wavefront luminous flux isreflected, and apart thereof is transmitted (for example, 5% of the fluxis transmitted, and 95% thereof is reflected), and most of the fundusillumination luminous flux and the fixation target luminous flux aretransmitted. Here, as an example, the wavelength of the first lightsource part 100 for wavefront luminous flux is 840 nm, the wavelength ofthe second light source part 110 for fundus illumination luminous fluxis 860 to 880 nm, the wavelength of the third light source part 91 forfixation target luminous flux is 500 nm, and the wavelength of the lightsource part 51 for anterior eye part observation is 940 nm, however, nolimitation is made to these.

Besides, as a modified example of the optical system, when constructionis made such that separation is performed in ascending order ofwavelength, the construction can be made by only high-pass filters(fixation target luminous flux, wavefront measurement luminous flux,fundus observation luminous flux, and anterior eye part illumination).Besides, when construction is made such that separation is performed indescending order of wavelength, the construction can be made by onlylow-pass filters (anterior eye part illumination, fundus observationluminous flux, wave front measurement luminous flux, and fixation targetluminous flux).

5. Display Example

FIG. 11 is an explanatory view showing a display example of a graphicdisplay on the display part 700.

Here, there is shown a state in which a first, a second and a thirddisplays of measurement results are respectively performed on thedisplay part 700 (for example, a display of a personal computer, etc.).On the display part 700, for example, the anterior eye part image, theHartmann image, and values of (S, C, Ax) as measurement results ofrefractive measurement are displayed.

“AUTO” in the drawing is a mode setting button for deciding an exposuretime automatically or manually. That is, when a proper user operatesthis mode setting button, for example, in the case where setting of theexposure time goes wrong, or in the case where measurement withdifferent light quantity and exposure time is desired, the manualsetting can be performed. At this time, the exposure time may bedirectly inputted, or levels are previously determined to a certaindegree and a level may be selected among them.

6. Measurement of Optical Characteristic

Next, the measurement of the optical characteristic at the steps S117and S119 of the foregoing flowchart will be described in detail.

FIG. 12 is a flowchart concerning Wavefront sensing using Shack-Hartmannmethod.

Specifically, for example, spot images are taken by the first lightreceiving part 510 (S6), and further, the barycentric position of eachof the spots is detected (S7). With respect to this barycentricposition, for example, a projected luminous flux is made to be projectedon plural pixels on the light receiving plane, and the barycentricposition can also be obtained by referring to the intensity of theluminous flux of each of the pixels. By calculating the barycenter asstated above, measurement position accuracy of {fraction (1/10)} or lessof the element can be ensured. Next, the amount of shift from abarycentric position of emmetropia is calculated (S8). Further, Zernikecoefficients are calculated (see JP-A-2001-204690) (S9).

Industrial Applicability

According to the present invention, as described above, it becomespossible to confirm at which position on the fundus of the eye to beexamined the luminous flux for measurement is converged or fixed, andfurther, the fixation target or the irradiation position of irradiationlight for wavefront sensing using Shack-Hartmann method is moved, sothat the converging position and the measurement position can bechanged, and the reliability of data can be further raised.

1. A device for measuring an optical characteristic of an eye,comprising: a first light source for emitting a luminous flux of a firstwavelength; a first illumination optical system for performingillumination by a first illumination luminous flux which is from thefirst light source and is converged to a vicinity of a center of afundus of an eye to be examined; a second light source for emitting aluminous flux of a second wavelength; a second illumination opticalsystem for illuminating an observation area of the fundus of the eye tobe examined by a second illumination luminous flux from the second lightsource; a beam splitter for branching a reflected luminous fluxreflected from the fundus of the eye to be examined into a first branchluminous flux containing most of the reflected luminous flux of thefirst wavelength and a second branch luminous flux containing aremaining portion of the reflected luminous flux of the first wavelengthand the reflected luminous flux of the second wavelength; a firstreception optical system for receiving the first branch luminous fluxbranched by the beam splitter and for guiding the first branch luminousflux so as to be received through a first conversion member forconverting it into at least 17 beams; a first light receiving part forreceiving the first branch luminous flux from the first receptionoptical system; a second reception optical system for guiding the secondbranch luminous flux branched by the beam splitter so as to be received;a second light receiving part for receiving the second branch luminousflux from the second reception optical system; an arithmetic part forobtaining the optical characteristic of the eye to be examined on thebasis of an inclination angle of the luminous flux obtained by the firstlight receiving part; and a display part for enabling confirmation of anirradiation position of the first illumination luminous flux on thefundus by a signal from the second light receiving part.
 2. A device formeasuring an optical characteristic of an eye according to claim 1,further comprising a fixation target projection optical system whichincludes a fixation target for forming a fixation target image on thefundus of the eye to be examined, enables a fixation target position tobe moved in a direction orthogonal to an optical axis, and is forinstructing to change a converging position of the first illuminationluminous flux on the fundus of the eye to be examined by movement of thefixation target.
 3. A device for measuring an optical characteristic ofan eye according to claim 1, further comprising a fixation targetprojection optical system which includes a fixation target for forming afixation target image on the fundus of the eye to be examined, and areflecting mirror having rotation axes in directions substantiallyorthogonal to each other in a vicinity of an imaging position of thefixation target, and is constructed to change a converging position ofthe first luminous flux on the fundus of the eye to be examined bymovement of the mirror.
 4. A device for measuring an opticalcharacteristic of an eye according to claim 1, wherein the firstillumination optical system includes a luminous flux directionconversion member, and a converging position of the first luminous fluxon the fundus of the eye to be examined is changed by a change in aluminous flux direction.
 5. A device for measuring an opticalcharacteristic of an eye according to claim 1, wherein the second lightsource part is a surface light source or a point light source having awavelength of 860 to 880 nm.
 6. A device for measuring an opticalcharacteristic of an eye according to claim 1, wherein the arithmeticpart judges whether a position of a fixation target image is near aposition of a macula.
 7. A device for measuring an opticalcharacteristic of an eye according to claim 2, wherein the second lightsource part is a surface light source or a point light source having awavelength of 860 to 880 nm.
 8. A device for measuring an opticalcharacteristic of an eye according to claim 3, wherein the second lightsource part is a surface light source or a point light source having awavelength of 860 to 880 nm.
 9. A device for measuring an opticalcharacteristic of an eye according to claim 4, wherein the second lightsource part is a surface light source or a point light source having awavelength of 860 to 880 nm.
 10. A device for measuring an opticalcharacteristic of an eye according to claim 2, wherein the arithmeticpart judges whether a position of a fixation target image is near aposition of a macula.
 11. A device for measuring an opticalcharacteristic of an eye according to claim 3, wherein the arithmeticpart judges whether a position of a fixation target image is near aposition of a macula.
 12. A device for measuring an opticalcharacteristic of an eye according to claim 4, wherein the arithmeticpart judges whether a position of a fixation target image is near aposition of a macula.
 13. A device for measuring an opticalcharacteristic of an eye according to claim 5, wherein the arithmeticpart judges whether a position of a fixation target image is near aposition of a macula.